Trends and disparities in cardiomyopathy-associated mortality among breast cancer adults aged ≥45 years in the United States, 1999–2023: CDC WONDER analysis.

e13141 Background: Breast cancer is the second leading cause of cancer death in the United States (US), with approximately 42,000 deaths annually. Although cardiotoxic therapies have improved survival, they may contribute to long-term cardiovascular mortality. Cardiomyopathy is a clinically important cause of morbidity and mortality among breast cancer survivors; however, national trends and disparities in cardiomyopathy-associated mortality in breast cancer patients amongst various demographic and geographic subgroups is unexplored. Methods: We performed a population-based analysis of US Multiple Cause of Death data from the CDC WONDER database (1999–2023). Deaths listing breast cancer (ICD-10 C50.x) and cardiomyopathy (ICD-10 I42.x) as contributing causes were included. Age-adjusted mortality rates (AAMRs) per 1,000,000 population were calculated using the 2000 U.S. standard population. Joinpoint regression identified temporal inflection points and estimated annual percent change (APC) and average annual percent change (AAPC). Analyses were stratified by sex, age (45–64 vs ≥65 years), race (non-Hispanic White and non-Hispanic Black), census region, urbanization, state, and place of death. Statistical significance was P < 0.05. Results: From 1999–2023, 9,568 cardiomyopathy-associated deaths occurred among individuals with breast cancer, with overall AAMR per 1,000,000 declining from 4.1 to 2.4 (APC -3.1) from 1999–2017, followed by an increase to 2.72 from 2017–2023 (APC 3.3); females followed a similar trend. Adults aged ≥65 years declined initially and increased from 2017–2023 (APC 3.4; AAMR 5.3-5.96), whereas those aged 45–64 years declined overall (AAMR 1.99-0.88). From 2017–2023, non-Hispanic Whites rose (APC 4.1; AAMR 2.23-2.73), whereas non-Hispanic Black or African Americans declined throughout 1999–2023 (APC 6.75−4.32). Regionally, Midwest and South declined from 1999-2023 (APC -1.9 and -2.1), while the West and Northeast declined initially and then increased after 2016 (APC 3.57 and 2.87). Metropolitan areas declined continuously (APC 4.37-2.86), whereas non-metropolitan areas increased from 2018-2020 (APC 21.2; AAMR 2.24-3.32). At the state level, Maryland had the highest AAMR (5.83) and Nevada the lowest (1.04) from 1999–2020; from 2021–2023, Minnesota had the highest (7.33) and Texas the lowest (2.03). Most deaths occurred in inpatient medical facilities (n = 3,379). Conclusions: Cardiomyopathy-associated mortality among breast cancer patients declined from 1999–2017 but subsequently increased in adults aged ≥65 years, females, non-Hispanic Blacks, non-metropolitan areas, and in the Midwest, Northeast, District of Columbia, and Minnesota. These populations may benefit from targeted cardio-oncology surveillance and proactive long-term cardiovascular risk management.